Functional decline in older breast cancer survivors treated with and without chemotherapy and non-cancer controls: results from the Hurria Older PatiEnts (HOPE) prospective study.

Purpose: This study aimed to assess whether physical functional decline in older women with early-stage breast cancer is driven by cancer, chemotherapy, or a combination of both.

Methods: We prospectively sampled three groups of women aged ≥ 65: 444 with early-stage breast cancer receiving chemotherapy (BC Chemo), 98 with early-stage breast cancer not receiving chemotherapy (BC Control), and 100 non-cancer controls (NC Control). Physical function was assessed at two timepoints (T1 [baseline] and T2 [3, 4, or 6 months]) using the Physical Functioning Subscale (PF-10) of the RAND 36-item Short Form. The primary endpoint was the change in PF-10 scores from T1 to T2, analyzed continuously and dichotomously (Yes/No, with "yes" indicating a PF-10 decline > 10 points, i.e., a substantial and clinically meaningful difference).

Results: Baseline PF-10 scores were similar across all groups. The BC Chemo group experienced a significant decline at T2, with a median change in PF-10 of -5 (interquartile range [IQR], -20, 0), while BC Control and NC Control groups showed a median change of 0 (IQR, -5, 5; p < 0.001). Over 30% of BC Chemo participants had a substantial decline in PF-10 vs. 8% in the BC Control and 5% in the NC Control groups (p < 0.001).

Conclusion: In this cohort of older adults with early-stage breast cancer, the combination of breast cancer and chemotherapy contributes to accelerated functional decline. Our findings reinforce the need to develop interventions aimed at preserving physical function, particularly during and after chemotherapy.

Implications For Cancer Survivors: The high prevalence of accelerated functional decline in older women undergoing breast cancer chemotherapy underscores the urgency to develop interventions aimed at preserving physical function and improving health outcomes.

Clinical Trial: NCT01472094, Hurria Older PatiEnts (HOPE) with Breast Cancer Study.